Saturday, January 26, 2008

Tide wasn't really very low yesterday, but after my last encounter with the six-armed sea star and the heart urchin during a similar tide last month, decided to take my chances to go to Changi Beach again. Together with me were LK, ST, SJ and my friend ZY.

Well, unfortunately didn't managed to find the above two critters again this time round, but we still managed to find all sorts of interesting animals :)

A cute little leaf porter crab. Mind you, I didn't turn it over, but found it swimming in this position. Apparently, this helped it to hide from predators swimming below. They are usually found in this position at dusk or when they are attracted to lights.

There were so many sand stars every where that we had to be really careful not to step onto them.

Found this pretty sand star, probably a different species, emerging from the sand. Sand stars are predators of little shells, and I've seen them feeding on button shells before.

Like Chek Jawa, we saw lots of sea hare eggs as well.

And also, many hairy sea hares. About one year ago, we saw many of these hairy sea hares and their eggs as well. Could this mean that they have a consistent yearly breeding cycle?

I lost count of the pink thorny sea cucumbers I saw too. Many of them had their feeding tentacles out.

Found several salmacis sea urchins among the seaweeds.

Some of the bare batches of sand has many sand dollars hidden underneath too.

As it got darker, the brittle stars also started appearing.

Found a patch of seaweeds with lots of whelks. There were probably thousands of them. What attracted them here? Food? Or Sex? Or both? Really have no idea.

Found several of these sea anemones.

But the highlight of trip must be this seahorse! I was busy scanning around for sea stars and heart urchins and have not really been searching closely for other well-camouflaged animals. Fortunately the rest of the gang were looking at things more closely though :P

As it got darker, some of the tiny sea stars started appearing too. The one above could be a juvenile biscuit sea star.

Not sure about this one though. Saw a tiny green sea star as well during my last trip here with JL, so was really delighted to see one again this time.

Also found this sea urchin stuck to a durian shell. Spikes against spikes :)

Only saw a few sea pencils this time. I guess most of them were probably found on the lower shore which wasn't exposed during yesterday's not-so-low tide.

Found this bristle worm towards the end of our exploration. Apparently the rest already saw quite a few of them.

When we walked over to the artificial rocky shore, we saw several purple climber crabs.

There were a few onchs too. These are not sea slugs (which refers to opistobranchs such as nudibranchs, sap-sucking slugs and sea hares), but marine pulmonate slugs more closely related to land snails that breathe air using simple lungs. Some species hide in air pockets among rocks during high tide, while some other species are able to burrow into the sand during high tide, forming form S-shaped tubes with an air pocket from which they breathe during immersion. It is known that a few species can breathe through their skin underwater too.

We also found this moon crab stuck among some rocks, high and dry because of the low tide. We later put it back into the water.

Tide was already rising then and we had to leave. While we couldn't find the six-armed sea star and the heart urchin, it was still a great day with many interesting sightings.

And after washing up, it's off to my favourite coffeeshop for my favourite teppanyaki! :)

Sunday, January 20, 2008

Guided at Chek Jawa for Nparks today, and with me were people from MND. We saw lots of interesting stuff, and guess I'll just highlight some of them today in this entry :)

And here's the gang at the top of the Jejawi Tower. Named after the nearby jejawi tree (also known as the Malayan banyan), the tower is about 20m tall, and gives a great view of the surrounding area.

After getting down from the tower, we entered the mangrove area, with swaying nipah palms (Nypa fruticans) growing on both sides of the boardwalk. We were quite lucky that one of the palm was flowering. Nipah palm, otherwise also called attap palm, is where you get your attap chee in your ice kacang from. During my kampong days, I used to live in an attap house which has a roof made from attap leaves :)

One sure sign that you are in a mangrove is when you see all these trees with exposed roots. The roots above belongs to the bakau trees (Rhizophora spp.). As the soil in a mangrove is usually very lacking in oxygen, mangrove trees adapt to this condition by having their roots exposed so as to take in oxygen from the air!

Near the end of the 500m-long mangrove boardwalk, we suddenly realised that we've entered crab territory. Hundreds of fiddler crabs (Uca spp.) were there waving their claws! And mind you, actually only the males have an enlarged claw. This claw is used to attract females, and also to intimidate other males.

Somehow we seem to have a lot of luck with elbow crabs (Family Parthenopidae) today. I saw at least five of them, despite that fact that they were usually so well camouflaged! Now, can you guess why they are called elbow crab? Just take a look at the pincers...

Several of my visitors were quite delighted to see the gong gongs (Laevistrombus canarium) in their natural habitat.

And of course, another familiar edible shell is the razor clam (Family Pharidae). Found it trying to burrow into the sand.

After the few days of heavy rainfall, I was quite relieved to see the resident carpet anemone (Stichodactyla haddoni)looking rather healthy. Hopefully we won't get another round of ultra heavy rainfall resulting in another mass death again...

Carpet anemones have sticky tentacles which trap animals that got too close to it. The tentacles has stinging cells that fire toxins into the animals to kill them. Acting like a conveyor belt system, the tentacles will also move the prey to the middle of the anemone, where the mouth is.

Found this sea cucumber again. Still, have no idea what species it is. Do you know that unlike us, sea cucumbers actually breathe through their backends?

As usual, there were lots of sand dollars (Arachnoides placenta) at the sand bar. They got their name because they look like coins.

And our first star of the day was this sand star (Astropecten sp.)! Quite surprised to see so many of them out so early, as most of the time they hide under the sand on a hot and bright day like this, and surface when it gets cooler and darker.

We were also quite fortunate that our hunter-seekers found us a seahorse (Hippocampus sp.) today!

Found a lot of these orange beehoon-like things among the seagrasses and seaweeds. These are sea hare eggs, and so I was expecting to see one of them along the way.

And indeed, we found a few hairy sea hares (Bursatella leachii)! Sea hares are basically snails with soft internal shells.

We also saw this sea star above, which for some time some of the guides had been wondering whether it's a juvenile cake sea star (Anthenea aspera) or a Gymnanthenea laevis, since it has the identifying features shared by both species. Personally I had thought it looked more like a cake sea star from its shape.

This time round, I finally remembered to take some close-ups of its upper surface to check for another identifying feature of a cake sea star that G. laevis lacks.

While it's not exactly super obvious, I was able to find some bivalved pedicellariae (those circled in red) on its top surface, and bigger versions were also present on its underside. Thus according to the "Guide to Sea Stars and Other Echinoderms of Singapore", this is most probably a juvenile cake sea star.

The hunter-seekers found two of these worms. Really have no idea what they are too. Hopefully some experts out there can answer me. They certainly didn't look like segmented worms to me, when another friend suggested that.

Yet another star find - a brittle star (Order Ophiuroidea)! And like its name, it is very brittle and its arms break off easily, so please handle it with care... Fortunately, they are able to regrow their broken arms though, but in the meantime, they will be at a disadvantage dealing with their everyday life with fewer arms.

And just before we got out of the intertidal area, we had a pleasant surprise of finding this cute little pink warty sea cucumber (Cercodemas anceps) hiding among some shells among the seaweeds!

After the walk at the jetty, we were given another treat from nature, with a few beams of sunlight peeping through the clouds, illuminating some boats in the distance.

What a way to end the day! Will be back at Chek Jawa to help KS on his project on Tuesday. Sure looking forward to see more great stuff!